1. Field
The invention is related to user controlled navigation. More particularly, the invention is related to the tracking of movements using a helmet.
2. Description of Related Art
Three-dimensional head input systems suitable for controlling a computer cursor rely on detection of signals transmitted from a head-mounted unit to a detection in order to position and/or orientation of the head. Generally, the three-dimensional head input systems have relied on detection of relative light beam intensities or arrival times of transmitted signals from a head unit to a receiver in order to calculate by standard triangulation algorithms the relative position coordinates and/or relative angular orientation of the user's head. Such transmitter/receiver detection systems have the limitation that they can be used to compute the head unit's position or its orientation, but not at the same time with accurate results.
To overcome these limitations, a system for three-dimensional navigation that uses complementary (two-way) position/angle detection to determine the coordinate position along the linear axes and angular orientation along rotational axes was developed. The system comprised a movable unit and a stationary unit. The movable unit is placed on the user's body so that user's movements can be used for three-dimensional navigation control. In U.S. Pat. No. 6,434,410, an embodiment is described in which a movable infrared emitter/detector is worn on the user's head and another stationary infrared emitter/detector is mounted on a stationary object such as a display.
Currently the preferred approach to providing helmet mounted control is used in the Joint Helmet Mounted Cueing system (JHMCS). The JHMCS uses a magnetic field head tracker that is mounted on a helmet. This requires magnetic field sensors mounted into the specialized helmet, and a magnetic field generator mounted inside the aircraft cockpit. The JHMCS system tracks the movement of the helmet within the magnetic field generated within the cockpit. The JHMCS is expensive, complex, and difficult to maintain.